The present disclosure relates to a packaging box that stores consumable supplies or the like.
Packaging boxes for consumable supplies and materials, such as a toner cartridge, are often unsealed by cutting along a breaking portion, such as a zipper, in order to clearly check whether or not the packaging box is unsealed. Such a packaging box is configured such that a cover provided with the breaking portion is adhered to a main body of the packaging box by an adhesive or the like. Therefore, the packaging box cannot be unsealed as long as the cover is not cut along the breaking portion. In addition, in order to reduce cost for the adhering processing of the cover to the main body, it is sometimes likely that the cover is constructed by an inner flap and an outer flap, a slit is provided in the inner flap, and an insertion piece that is inserted into and engaged with the slit is provided in the outer flap. The insertion piece is formed with an engaging piece configured to be insertable into the slit by being folded and to be unfolded after the insertion into the slit to prevent the insertion piece from being pulled out of the slit.
The above packaging box will be described with reference to FIG. 7A, FIG. 7B and FIG. 7C. As shown in FIG. 7A, along a tip edge of an outer flap 100, an insertion piece 102 is connected via a bending line 101, and along both side edges of the insertion piece 102, engaging pieces 104 are respectively connected via folding lines 103. On the other hand, an inner flap 110 is formed with a slit 111 into which the insertion piece 102 is inserted. A predetermined gap G is provided between the tip edge of the outer flap 100 and each of the engaging pieces 104. Therefore, the engaging pieces 104 can be unfolded without interfering with the slit 111 after the insertion of the insertion piece 102 into the slit 111.
However, in such a packaging box, there is a risk that if the gap G between the tip edge of the outer flap 100 and each of the engaging pieces 104 is large, the outer flap 100 is opened by its elasticity after each of the engaging pieces 104 is retained in the slit 111, and, as shown in FIG. 7B, a gap g is formed between the outer flap 100 and the inner flap 110, and the packaging box is mistaken as being unsealed. In a packaging box having a large lateral width, the gap g is particularly likely to be conspicuous.
In addition, the engaging pieces 104 are folded along the folding lines 103 extending in a direction orthogonally crossing the tip edge of the outer flap 100. However, if the engaging pieces 104 are unevenly folded, as shown in FIG. 7C, there is a risk that apart of the engaging pieces 104 is caught on the slit 111, the engaging pieces 104 are not opened after the insertion of the insertion piece 102 into the slit 111, and thus the outer flap 100 cannot be surely engaged with the inner flap 110.